The shrinkage method is often used for the assembly of rolling bearings. For example, if a rolling bearing is to be assembled on a shaft, then said rolling bearing is firstly heated. On account of thermal expansion, said rolling bearing then has a slightly larger inner diameter. In contrast, the shaft remains at room temperature or is possibly cooled in order to then have a smaller outer diameter. The shaft and the rolling bearing are dimensioned such that the rolling bearing can be pushed onto the shaft only as a result of the slight inner diameter enlargement. After the rolling bearing is pushed on, it cools and the inner diameter decreases in size. The rolling bearing and shaft are now connected to one another in a frictionally engaging manner; this is also referred to as a shrink fit. If heating occurs during operation, the rolling bearing and the shaft will be heated at the same time on account of their spatial proximity and the heat conduction between them. If the coefficients of thermal expansion are equal or similar, then the rolling bearing and the shaft will also expand to approximately the same extent, such that the frictionally engaging connection is maintained. A connection of said type has the advantages that it can absorb very high forces and that no further connecting parts are required.
The heating of the rolling bearing takes place conventionally by means of heating plates, welding torches, furnaces, inductive heating devices and the like. The temperature of the rolling bearing must, after heating, be sufficiently high that the resulting enlargement of the inner diameter allows said rolling bearing to be assembled by being pushed on. However, the temperature may not become so large that the bearings are damaged or destroyed. Here, particular attention must be paid to any lubricant which may have been introduced. Once the rolling bearing has reached the assembly temperature, the assembly process must take place quickly, since the rolling bearing cools quickly after the removal of the heat source and the inner diameter begins to decrease in size. Should the rolling bearing, as it is assembled on the shaft, have already cooled to such an extent that it can no longer be moved before the final position has been reached, then the bearing usually becomes unusable. Said bearing can often only be removed from the shaft by being damaged or destroyed. In some cases, the shaft also becomes unusable.
The heating of the rolling bearing can, in complex devices, take place by means of regulable heating plates with which the temperature can be preselected within small tolerance ranges. In contrast, if simple heating plates, furnaces or welding torches are used, the risk of destroying the rolling bearing as a result of an excessively high temperature, or the risk of unsuccessful assembly on account of an excessively low temperature, is considerably increased. In all known methods for forming a shrink fit of rolling bearings, it is always necessary to depend on external devices for heating, which is a long-established disadvantage of said type of connection for rolling bearings.
The invention is therefore based on the object of providing a rolling bearing whose rolling bearing ring which is to be shrunk onto a shaft or onto a similar frame element can be heated to an assembly temperature without external devices and which can, if required, be held at said temperature for a certain period of time. One part-object is considered to be that of also ensuring an optimum temperature in start-up phases during later operation, in particular of providing an additional heat supply in the bearing.